The FDA approved the drug in November 2014 for the treatment of the Philadelphia chromosome-negative form of the disease, after trial results showed that 32% of patients had complete remission for approximately 6.7 months. It was granted priority review and breakthrough therapy designations by the regulator.

This made it the first approved drug that engages the body’s T-cell to destroy leukaemia cells.

However the drug is one of the world’s most expensive cancer treatments, coming in at around $178,000 for two courses of treatment – the amount that it took to achieve complete remission in the latest trial.